I have two associative arrays with string keys, like this:
$base_array = array(
'foo' => '42',
'bar' => '13');
and
$update_array = array(
'bar' => '14',
'blah' => '3.1415');
Question 1: I want to update my $base_array with data from $update_array in such a way that:
If a key is only in $base_array, but not in $update_array, its value be kept intact;
If a key is in both arrays, its value be updated from $update_array;
If a key is only in $update_array, both the key and its value be copied into $base_array.
Is there a short way to accomplish this? Any hint or piece of code is very welcome.
Question 2: Besides this, is there a quick way to visualize a joint list of keys from both arrays, without duplicates? Just keys, no values.
Question 1:
That is exactly what array_merge() does:
$new_array = array_merge($base_array,$update_array);
Question 2:
To get an array of the unique keys, you can merge the arrays and then use array_keys():
$keys = array_keys(array_merge($base_array,$update_array));
Related
Is there a standard PHP function that changes an associative array's index names?
$a1 = array('one'=>1,'two'=>2,'three'=>3);
$new_index_names = array('one'=>'ono','two'=>'dos','three'=>'tres');
$a2 = change_index_names($a1,$new_index_names);
print_r($a2);
// $a2 should have the index names changed accordingly and look like this:
// array('ono'=>1,'dos'=>2,'tres'=>3)
EDIT
Please note that the function needs to know the mappings to the new index names. Meaning, in $new_index_names array provides the mappings. So again, it needs to know that 'ono' is the new index name for 'one'.
EDIT
I know you guys can come up with your own solution, i was wondering there is a standard PHP function that already does this.
EDIT
There are several situations where changing index names would help:
1) separates post value names to generic/internal names so you can separate
your backend code from front-end code.
2) say for instance you have two arrays from post that need to go through the
same exact process, except both arrays although mean/contain same exact type
of values/order/structure, they're index names are different. So when
passing to a function/method that goes by only a set of index names, you'll
need to convert the index names before passing them to that function/method.
You don't need array_values To get your desired output you can just use
array_combine($new_index_names,$a1);
not in just 1 function, but you could use array_values to get the values of the first array, and array_combine to set the new keys
Assuming both arrays has equal count, one way is with array_combine() and array_values()
$a2 = array_combine(array_values($new_index_names), $a1);
The previous answers does not consider the order of $a1 and $new_index_names, so I put my solution following:
$a1 = array('one' => 1, 'two' => 2, 'three' => 3, 'zero' => 0);
$new_index_names = array('zero' => 'zero', 'one' => 'ono', 'two' => 'dos', 'three' => 'tres');
array_combine(
$new_index_names,
str_replace(array_keys($a1), array_values($a1), array_keys($new_index_names))
);
Array
(
[zero] => 0
[ono] => 1
[dos] => 2
[tres] => 3
)
The best answer I've seen thus far:
foreach ($a1 as $k => $v) $a2[$new_index_names[$k]] = $v;
Credits go to jh1711
I have several associative arrays in PHP that looks like this:
$data1 = array("foo" => "one", "animal" => "mice");
$data2 = array("foo" => "two", "animal" => "cats");
....
I want to create another associative array, using the serialized values of the previous arrays are used as the array keys. For example:
$newArray = array("data1's serialized key" => "someNewValue", ... );
Are serialized arrays suitable for being used as array keys?
Do they contain any unacceptable characters?
Do I need to do something more to the serialized string to make it acceptable as an array key (while still keeping its uniqueness)?
Are serialized arrays suitable for being used as array keys?
Yup! As far as I know you can use serialized arrays as a key in another array. But the I cannot think of any use-case for this. :P
Do they contain any unacceptable characters?
No, until and unless you specify any unacceptable characters in the original array.
Do I need to do something more to the serialized string to make it acceptable as an array key (while still keeping its uniqueness)?
Nope.
So, you code would look like:
$data1 = array("foo" => "one", "animal" => "mice");
$data2 = array("foo" => "two", "animal" => "cats");
$serializedArrayKey1 = serialize($data1);
$serializedArrayKey2 = serialize($data2);
$newArray = array($serializedArrayKey1 => "Value for data1", ...);
The question pretty much says it all.
Im trying to match the keys of one array, to the values of another in php, without the use of a loop. Thanks :)
I could create an array by naming all the keys to the value i want to match against and set the value to null and check the key intersection, but this just seems inefficient. There probably is a simpler way to it, if anyone knows :)
For example
$array1 = array('photo' => 'foo.jpeg', 'audio' => 'bar.mp3');
$array2 = array('photo', 'audio', 'video');
Im trying to get any value of $array2 to match with any of the keys of $array1
Try these methods.
<?php
$a = array_keys( array('photo' => 'foo.jpeg', 'audio' => 'bar.mp3') );
$b = array('photo', 'audio', 'video');
//This will return empty array
print_r(array_values( array_diff($a, $b) ));
//This will return array with "video".
print_r(array_values( array_diff($b, $a) ));
//This will check Double sided array so the response
// will be element missing from both arrays.
print_r(array_values(array_merge(array_diff($b, $a), array_diff($a, $b))));
I stuck with a problem: I have an array with IDs and want to assign theses IDs to a key of a associative array:
$newlinkcats = array( 'link_id' => $linkcatarray[0], $linkcatarray[1], $linkcatarray[2]);
this works fine, but I don't know how many entries in $linkcatarray. So I would like to loop or similar. But I don't know how.
no push, cause it is no array
no implode, cause it is no string
no =, cause it overrides the value before
Could anyone help?
Thanks
Jim
Why not just implode it ?
$newlinkcats = array(
'link_id' => implode(
',',
$linkcatarray
)
);
Or just do this:
// Suggested by Tularis
$newlinkcats = array(
'link_id' => $linkcatarray
);
If your $linkcatarray array is only comprised of the values you wish to assign to the link_id key, then you can simply point the key at that array:
$newlinkcats = array('link_id' => $linkcatarray);
If that array contains more values that you don't want included, then take a look at array_slice() to only grab the indexes you need:
// Grabs the first 3 values from $linkcatarray
$newlinkcats = array('link_id' => array_slice($linkcatarray, 0, 3));
If your desired indexes aren't contiguous, it may be easier to cherry-pick them and use a new array:
$newlinkcats = array('link_id' => array(
$linkcatarray[7],
$linkcatarray[13],
$linkcatarray[22],
// ...
));
array(
[0]
name => 'joe'
size => 'large'
[1]
name => 'bill'
size => 'small'
)
I think i'm being thick, but to get the attributes of an array element if I know the value of one of the keys, I'm first looping through the elements to find the right one.
foreach($array as $item){
if ($item['name'] == 'joe'){
#operations on $item
}
}
I'm aware that this is probably very poor, but I am fairly new and am looking for a way to access this element directly by value. Or do I need the key?
Thanks,
Brandon
If searching for the exact same array it will work, not it you have other values in it:
<?php
$arr = array(
array('name'=>'joe'),
array('name'=>'bob'));
var_dump(array_search(array('name'=>'bob'),$arr));
//works: int(1)
$arr = array(
array('name'=>'joe','a'=>'b'),
array('name'=>'bob','c'=>'d'));
var_dump(array_search(array('name'=>'bob'),$arr));
//fails: bool(false)
?>
If there are other keys, there is no other way then looping as you already do. If you only need to find them by name, and names are unique, consider using them as keys when you create the array:
<?php
$arr = array(
'joe' => array('name'=>'joe','a'=>'b'),
'bob' => array('name'=>'bob','c'=>'d'));
$arr['joe']['a'] = 'bbb';
?>
Try array_search
$key = array_search('joe', $array);
echo $array[$key];
If you need to do operations on name, and name is unique within your array, this would be better:
array(
'joe'=> 'large',
'bill'=> 'small'
);
With multiple attributes:
array(
'joe'=>array('size'=>'large', 'age'=>32),
'bill'=>array('size'=>'small', 'age'=>43)
);
Though here you might want to consider a more OOP approach.
If you must use a numeric key, look at array_search
You can stick to your for loop. There are not big differences between it and other methods – the array has always to be traversed linearly. That said, you can use these functions to find array pairs with a certain value:
array_search, if you're there's only one element with that value.
array_keys, if there may be more than one.